If no sound can be heard while playing YouTube videos, try these troubleshooting steps:
．Adjust speaker or computer volume.
．Adjust the volume control located in the lower left corner of the YouTube video player.
．Adjust volume on the video player (e.g. Quicktime, Realplayer or Windows Media player).
If still no sound is available after trying the troubleshooting steps above, these additional tips may help:
．Update your Flash Player to the latest version.
．Allow third-party Flash content to store data on your computer: Please visit Adobe main website for more information.
．Check security settings to see if third-party Flash content is blocked by anti-virus softwares or firewalls.